The escalating HIV/AIDS epidemic worldwide demands that on-going prevention efforts be strengthened, disseminated, and scaled-up. System-level interventions refer to programs aiming to improve the functioning of an agency as well as the delivery of its services to the community. System-level interventions are a promising approach to HIV/AIDS prevention because they focus on (a) improving the agency's ability to adopt evidence-based HIV prevention and care programs; (b) develop and establish policies and procedures that maximize the sustainability of on-going prevention and care efforts; and (c) improve decision-making processes such as incorporating the needs of communities into their tailored services. We reviewed studies focusing on system-level interventions by searching multiple electronic abstracting indices, including PsycInfo, PubMed, and ProQuest. Twenty-three studies out of 624 peer-reviewed studies (published from January 1985 to February 2007) met study criteria. Most of the studies focused on strengthening agency infrastructure, while other studies included collaborative partnerships and technical assistance programs. Our findings suggest that system-level interventions are promising in strengthening HIV/AIDS prevention and treatment efforts. Based on our findings, we propose recommendations for future work in developing and evaluating system-level interventions.